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Fencer Vulns
high 7.5

CVE-2023-3354 json

Improper i/o watch removal in tls handshake can lead to remote unauthenticated denial of service

published 2023-07-11 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-44021

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 76%
public exploits
0
none known

Summary

A flaw was found in the QEMU built-in VNC server. When a client connects to the VNC server, QEMU checks whether the current number of connections crosses a certain threshold and if so, cleans up the previous connection. If the previous connection happens to be in the handshake phase and fails, QEMU cleans up the connection again, resulting in a NULL pointer dereference issue. This could allow a remote unauthenticated client to cause a denial of service.

Patch / fix

  • qemu qemu 8.1.0
  • qemu Debian 12 1:7.2+dfsg-7+deb12u2
  • qemu Debian 14, Debian 13 1:8.0.4+dfsg-1

debian advisories DEBIAN-CVE-2023-3354

  • qemu Ubuntu 20.04 LTS 1:4.2-3ubuntu6.28
  • qemu Ubuntu 22.04 LTS 1:6.2+dfsg-2ubuntu6.16
  • qemu Ubuntu Pro 18.04 LTS 1:2.11+dfsg-1ubuntu7.42+esm5

ubuntu advisories UBUNTU-CVE-2023-3354

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • SLOF RHEL 8 20210217-1.module+el8.8.0+16781+9f4724c2
  • hivex RHEL 8 1.3.18-23.module+el8.8.0+16781+9f4724c2
  • netcf RHEL 8 0.2.8-12.module+el8.8.0+16781+9f4724c2
  • swtpm RHEL 8 0.7.0-4.20211109gitb79fd91.module+el8.8.0+16781+9f4724c2
  • libnbd RHEL 8 1.6.0-5.module+el8.8.0+16781+9f4724c2
  • nbdkit RHEL 8 1.24.0-5.module+el8.8.0+17308+05924798
  • libtpms RHEL 8 0.9.1-2.20211126git1ff6fe1f43.module+el8.8.0+18453+1482ba89
  • libvirt RHEL 8 8.0.0-19.2.module+el8.8.0+18944+7f5acf75

red hat advisories RHSA-2024:0404RHSA-2023:5587RHSA-2023:5796RHSA-2023:5239RHSA-2023:5264RHSA-2023:6227

  • qemu SLES for SAP 12 SP5, SLES 12 SP5 3.1.1.1-72.1
  • qemu SLE Module for Server Applications 15 SP5, SLE Module for Package Hub 15 SP5, SLE Module for Basesystem 15 SP5 +2 more 7.1.0-150500.49.9.2
  • qemu SLE Module for Server Applications 15 SP4, SLE Module for Basesystem 15 SP4, SLE Micro 5.4 +2 more 6.2.0-150400.37.23.1
  • qemu SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE High Performance Computing 15 SP2-LTSS +1 more 4.2.1-150200.79.1
  • qemu SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +6 more 5.2.0-150300.127.3
  • qemu SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLE High Performance Computing 15 SP1-LTSS 3.1.1.1-150100.80.51.5

suse advisories SUSE-SU-2024:1395-1SUSE-SU-2024:0589-1SUSE-SU-2023:4662-1SUSE-SU-2023:4056-1SUSE-SU-2023:3800-1SUSE-SU-2023:3721-1

  • qemu openSUSE Tumbleweed 8.0.4-1.1

opensuse advisories openSUSE-SU-2024:13114-1

  • SLOF AlmaLinux 8 20210217-1.module_el8.6.0+2880+7d9e3703
  • hivex AlmaLinux 8 1.3.18-23.module_el8.6.0+2880+7d9e3703
  • hivex AlmaLinux 8 1.3.18-23.module_el8.6.0+3161+a07c0ea5
  • netcf AlmaLinux 8 0.2.8-12.module_el8.6.0+2880+7d9e3703
  • netcf AlmaLinux 8 0.2.8-12.module_el8.6.0+3161+a07c0ea5
  • swtpm AlmaLinux 8 0.7.0-4.20211109gitb79fd91.module_el8.7.0+3346+68867adb
  • libnbd AlmaLinux 8 1.6.0-5.module_el8.6.0+2880+7d9e3703
  • libnbd AlmaLinux 8 1.6.0-5.module_el8.6.0+3161+a07c0ea5

almalinux advisories ALSA-2023:5264ALSA-2023:5094

  • hivex Rocky Linux 8 1.3.18-23.module+el8.10.0+1835+43f01cbb
  • hivex Rocky Linux 8 1.3.18-23.module+el8.10.0+1590+a67ab969
  • netcf Rocky Linux 8 0.2.8-12.module+el8.10.0+1590+a67ab969
  • netcf Rocky Linux 8 0.2.8-12.module+el8.10.0+1835+43f01cbb
  • swtpm Rocky Linux 8 0.7.0-4.20211109gitb79fd91.module+el8.10.0+1835+43f01cbb
  • swtpm Rocky Linux 8 0.7.0-4.20211109gitb79fd91.module+el8.10.0+1590+a67ab969
  • libnbd Rocky Linux 8 1.6.0-5.module+el8.10.0+1590+a67ab969
  • libnbd Rocky Linux 8 1.6.0-5.module+el8.10.0+1835+43f01cbb

rocky linux advisories RLSA-2023:5264

  • qemu CBL-Mariner 2.0 6.2.0-19
  • qemu Azure Linux 3.0 8.2.0-1

azure linux advisories AZL-31659AZL-35171

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-3354 updated cvss 7.5

QEMU: VNC: improper I/O watch removal in TLS handshake can lead to remote unauthenticated denial of service

  • Red Hat Enterprise Linux 7 qemu-img-ma, qemu-kvm-ma, qemu-kvm-tools-ma, qemu-kvm-common-ma Red Hat Enterprise Linux 8 Advanced Virtualization qemu-img, qemu-kvm, qemu-kiwi, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, +9 more Red Hat OpenStack Platform 13 (Queens) qemu-img-rhev, qemu-kvm-rhev, qemu-kvm-tools-rhev, qemu-kvm-common-rhev
    affected: no fix available
  • Red Hat CodeReady Linux Builder EUS (v.8.6) libnbd 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, netcf 0.2.8-12.module+el8.6.0+14480+c0a3aa0f, hivex 1.3.18-23.module+el8.6.0+14480+c0a3aa0f, nbdfuse 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, SLOF 20210217-1.module+el8.6.0+14480+c0a3aa0f, libiscsi 1.18.0-8.module+el8.6.0+14480+c0a3aa0f, +38 more
    fixed: vendor fix RHSA-2024:0404
  • Red Hat Enterprise Linux AppStream (v. 8) libnbd 1.6.0-5.module+el8.8.0+16781+9f4724c2, netcf 0.2.8-12.module+el8.8.0+16781+9f4724c2, hivex 1.3.18-23.module+el8.8.0+16781+9f4724c2, nbdfuse 1.6.0-5.module+el8.8.0+16781+9f4724c2, nbdkit 1.24.0-5.module+el8.8.0+17308+05924798, SLOF 20210217-1.module+el8.8.0+16781+9f4724c2, +104 more
    fixed: vendor fix RHSA-2023:5264
  • Red Hat Enterprise Linux AppStream (v. 9) qemu-img 7.2.0-14.el9_2.5, qemu-kvm 7.2.0-14.el9_2.5, qemu-kvm-core 7.2.0-14.el9_2.5, qemu-kvm-tools 7.2.0-14.el9_2.5, qemu-pr-helper 7.2.0-14.el9_2.5, qemu-kvm-common 7.2.0-14.el9_2.5, +12 more
    fixed: vendor fix RHSA-2023:5094
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) hivex 1.3.15-7.module+el8.1.0+4066+0f1aadab, nbdkit 1.4.2-5.module+el8.1.0+4066+0f1aadab, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, seabios 1.11.1-4.module+el8.1.0+4066+0f1aadab, libiscsi 1.18.0-8.module+el8.1.0+4066+0f1aadab, supermin 5.1.19-9.module+el8.1.0+4066+0f1aadab, +79 more
    fixed: vendor fix RHSA-2023:5587
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) libnbd 1.2.2-1.module+el8.3.0+7353+9de0a3cc, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, nbdfuse 1.2.2-1.module+el8.3.0+7353+9de0a3cc, nbdkit 1.16.2-4.module+el8.3.0+6922+fd575af8, hivex 1.3.18-21.module+el8.4.0+10770+19c037f9, seabios 1.13.0-2.module+el8.3.0+7353+9de0a3cc, +87 more
    fixed: vendor fix RHSA-2023:5796
  • Red Hat Enterprise Linux AppStream E4S (v. 8.1) hivex 1.3.15-7.module+el8.1.0+4066+0f1aadab, nbdkit 1.4.2-5.module+el8.1.0+4066+0f1aadab, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, seabios 1.11.1-4.module+el8.1.0+4066+0f1aadab, libiscsi 1.18.0-8.module+el8.1.0+4066+0f1aadab, supermin 5.1.19-9.module+el8.1.0+4066+0f1aadab, +81 more
    fixed: vendor fix RHSA-2023:5239
  • Red Hat Enterprise Linux AppStream E4S (v. 8.2) hivex 1.3.15-7.module+el8.1.0+4066+0f1aadab, nbdkit 1.4.2-5.module+el8.1.0+4066+0f1aadab, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, seabios 1.11.1-4.module+el8.1.0+4066+0f1aadab, libiscsi 1.18.0-8.module+el8.1.0+4066+0f1aadab, supermin 5.1.19-9.module+el8.1.0+4066+0f1aadab, +80 more
    fixed: vendor fix RHSA-2023:5587
show 7 more
  • Red Hat Enterprise Linux AppStream E4S (v.8.4) libnbd 1.2.2-1.module+el8.3.0+7353+9de0a3cc, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, nbdfuse 1.2.2-1.module+el8.3.0+7353+9de0a3cc, nbdkit 1.16.2-4.module+el8.3.0+6922+fd575af8, hivex 1.3.18-21.module+el8.4.0+10770+19c037f9, seabios 1.13.0-2.module+el8.3.0+7353+9de0a3cc, +88 more
    fixed: vendor fix RHSA-2023:5796
  • Red Hat Enterprise Linux AppStream EUS (v.8.6) libnbd 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, netcf 0.2.8-12.module+el8.6.0+14480+c0a3aa0f, hivex 1.3.18-23.module+el8.6.0+14480+c0a3aa0f, nbdfuse 1.6.0-5.module+el8.6.0+14480+c0a3aa0f, nbdkit 1.24.0-4.module+el8.6.0+14480+c0a3aa0f, SLOF 20210217-1.module+el8.6.0+14480+c0a3aa0f, +104 more
    fixed: vendor fix RHSA-2024:0404
  • Red Hat Enterprise Linux AppStream EUS (v.9.0) qemu-img 6.2.0-11.el9_0.8, qemu-kvm 6.2.0-11.el9_0.8, qemu-kvm-core 6.2.0-11.el9_0.8, qemu-kvm-tools 6.2.0-11.el9_0.8, qemu-pr-helper 6.2.0-11.el9_0.8, qemu-kvm-common 6.2.0-11.el9_0.8, +15 more
    fixed: vendor fix RHSA-2023:6227
  • Red Hat Enterprise Linux AppStream TUS (v. 8.2) hivex 1.3.15-7.module+el8.1.0+4066+0f1aadab, nbdkit 1.4.2-5.module+el8.1.0+4066+0f1aadab, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, seabios 1.11.1-4.module+el8.1.0+4066+0f1aadab, libiscsi 1.18.0-8.module+el8.1.0+4066+0f1aadab, supermin 5.1.19-9.module+el8.1.0+4066+0f1aadab, +79 more
    fixed: vendor fix RHSA-2023:5587
  • Red Hat Enterprise Linux AppStream TUS (v.8.4) libnbd 1.2.2-1.module+el8.3.0+7353+9de0a3cc, netcf 0.2.8-12.module+el8.1.0+4066+0f1aadab, nbdfuse 1.2.2-1.module+el8.3.0+7353+9de0a3cc, nbdkit 1.16.2-4.module+el8.3.0+6922+fd575af8, hivex 1.3.18-21.module+el8.4.0+10770+19c037f9, seabios 1.13.0-2.module+el8.3.0+7353+9de0a3cc, +87 more
    fixed: vendor fix RHSA-2023:5796
  • Red Hat Enterprise Linux CRB (v. 8) libnbd 1.6.0-5.module+el8.8.0+16781+9f4724c2, netcf 0.2.8-12.module+el8.8.0+16781+9f4724c2, hivex 1.3.18-23.module+el8.8.0+16781+9f4724c2, nbdfuse 1.6.0-5.module+el8.8.0+16781+9f4724c2, SLOF 20210217-1.module+el8.8.0+16781+9f4724c2, seabios 1.16.0-4.module+el8.8.0+19627+2d14cb21, +38 more
    fixed: vendor fix RHSA-2023:5264
  • Red Hat Enterprise Linux 6 qemu-img, qemu-kvm, qemu-kvm-tools, qemu-guest-agent, qemu-guest-agent-win32 Red Hat Enterprise Linux 7 qemu-img, qemu-kvm, libcacard, qemu-kvm-tools, libcacard-tools, qemu-kvm-common, +1 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.61% chance of exploitation in the next 30 days, higher than 76% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • n/a qemu
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 8 Advanced Virtualization
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat OpenStack Platform 13 (Queens)
  • Fedora Fedora
  • Fedora Extra Packages for Enterprise Linux

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.